Technical Field
The present invention relates to a method and apparatus for controlling a current of a multi-phase interleaved converter and, more particularly, to a method and apparatus for controlling a current of a multi-phase interleaved converter to reduce load on a Micro Controller Unit (MCU) ( )and redress a current imbalance of a multi-phase interleaved converter.
Background Art
Today, direct current to direct current (DC/DC) converters are applied to various electric power converters such as vehicle battery chargers. When a voltage is boosted using a DC/DC converter, a ripple current may occur in the inductor of the converter. Such a ripple current affects the size constraints of elements such as inductors and capacitors, and is closely related with an amount of power loss. Interleaving refers to a method in which the mix of currents flowing with different phases causes their ripple currents to be offset by one another, to cause the combined ripple current to decrease in magnitude by 1/N times whereas the frequency increases by N times; where N denotes the number of phases.
An interleaved converter connects multiple DC/DC converters in parallel to disperse electric current and uses the phase difference of switching elements to reduce the magnitude and ripple of currents flowing through elements such as inductors. The converter may disperse electric current and allow an appropriate level of phase difference for the current, to significantly decrease the ripple of input and output currents. In addition, the use of such an interleaved converter may increase energy efficiency and adjust the size of elements in the circuit.
An interleaved converter generally has a structure similar to a parallel connection of multiple single-phase converters. For example, in a three-phase interleaved converter, each switch operates with a phase difference of 120 degrees. An N-phase interleaved converter has the same structure as the parallel connection of N single-phase converters, in which each switch operates with a phase difference of (2π/N)(rad). In an interleaved converter, an increase in the number of phases may require an increase in the number of elements needed in the circuit.
There are two methods of controlling a current of interleaved converters which include: sensing a multi-phase current on multiple phases and applying current controllers that correspond to respective phases to generate duty ratios for respective phases; and applying a current controller for one phase to phase-shift the same duty ratio for other phases by a fixed size. However, in the first method, separate current controllers are required for respective phases, thus increasing the load on the
MCU. In the second method, a current change in a phase having no current controller may be difficult to reflect.